Briggs: My rebuttal is in the comments.
For centuries, a welter of Christian, Jewish, and Islamic commentators, with nary a whimper from their “common sense,” dutifully repeated Aristotle’s statement in On the Heavens (I.vi) that of two bodies the one with twice the mass will fall from the same height in one-half the time. And they rarely if ever seemed to notice how radically insufficient Aristotle’s understanding of motion had to be for him to make that statement about what happens to bodies when they fall.
For centuries, a welter of devout Catholic theologians, in discussion of the source and summit of Catholic life, the Holy Sacrifice of the Mass, the Eucharist, have dutifully repeated St. Thomas’s placement of all sacramental efficacy in the words of consecration: “This is my Body; This is my Blood.” And similarly, they too have rarely seemed even to notice how radically insufficient St. Thomas’s metaphysical system had to be for him to make his argument about the Eucharist.
For not even a genius of St. Thomas’s caliber was able to deploy that Aristotelian analysis to account for the simple Catholic facts of the matter without generating contradictions.
Thus St. Thomas’s argument on this point refutes — not merely eviscerates, but refutes — any possible use of Aristotle’s brand of form-matter analysis in Catholic theology.
… if we take seriously the meaning of form and matter in the Thomist act-potency analysis, it is clear that only by the “form” of the sacramental sign (sacramentum tantum), viz., by the words of consecration, do the bread or the wine signify and cause what they signify. That the bread and wine, as signs, are indispensable to this efficacy must be conceded—and in fact this is insisted upon over and again by St. Thomas, for if the bread or the wine is corrupt, or substituted for by invalid matter, there is no sacrament—but he provides no act-potency explanation for their indispensability. If the words of consecration are truly the formal content of the sacramental sign, the matter upon which they bear cannot but be formally insignificant; as material causes, they can do no more than individuate the sign in space and time, for which purpose any material whatever would suffice.
[ Rev. Donald Keefe, SJ, Covenantal Theology Vol. II, Ch. 5, pp. 422 ]
St. Thomas finds himself in a pickle. Supporting wholeheartedly the clear and constant profession of the Catholic Church, he affirms repeatedly that the bread and wine are indispensable to the efficacy of the sacrament, and he also must affirm, by the Aristotelian form-matter analysis that he wants to deploy, that as material causes, the bread and wine are completely dispensable.
According to the metaphysics of Aristotle, the bread and wine can be any material whatever, but according to the Catholic Church, this is a complete falsity, a gigantic heresy, an outright absurdity, with numerous and deep implications for the whole of Catholic profession and life. It’s difficult to imagine saying that “in principle” the bread and wine could be anything whatever, and remaining any kind of Catholic at all. It’s that far removed from the “this-ness” of real Catholicism.
But this is precisely what the Aristotelian metaphysics forces. So (following his Catholic faith) St. Thomas says that the bread and wine are very specifically indispensable to the sacrament, but (following Aristotle) he must simultaneously say that it is impossible for the bread and wine to be indispensable; for they lack a formal “subject of inherence.”
This contradiction, out of St. Thomas’s own mouth, and regarding the Eucharist itself, the very heart of the Catholic Church, refutes “Thomism” root and branch. The Aristotelian form-matter analysis is radically insufficient to Catholic theology. The proof by contradiction is complete.
It is true that I have never read, nor met, any Thomist dumb enough to fall for such a simple, clear, “inclined plane”, “balls dropped from the tower” refutation of an entire theory. Thomists are far too intelligent, too highly trained, even to be bothered, let alone intrigued, by a parlor trick.
Nonetheless, Fr. Keefe himself was optimistic:
…the first step toward the conversion of cosmology to a Christian metaphysics was taken by St. Thomas himself, without which no Thomism would exist and no progress in it would be possible. To refuse to proceed further is to hesitate where St. Thomas did not, whose great respect for “the Philosopher” did not prevent his undertaking a theological–and therefore a historical–systematic project. If we are to continue what Thomas began, we must recognize that he left unfinished the conversion of the Aristotelian cosmology which constitutes his metaphysics.
[ ibid. p. 423 ]
About Fr Keefe, see Kelleher’s earlier post.